log4j-api-java9.pom and log4j-core-java9.pom sometimes cause maven enforcer to fail

Log4j API and Log4j Core have to build the Java 9 classes in one Maven module and then copy them into the "normal" module. The Java 9 projects are not deployed during a release. The pom.xml files were specifying both as provided dependencies. When the enforcer plugin sees this it is trying to resolve them - sometimes - and fails. It seems these don't need to be declared as dependencies because they are configured into the dependency plugin. So the dependencies should be removed from the pom files.